[FONT="]Nhờ anh chị lấy giúp em 2 bài này
[/FONT]http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CTN-4BT8FD9-7&_user=10&_coverDate=12/31/2003&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1574302749&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=14d25cbd30f3794187ea53e6dc148d3f&searchtype=a
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[/FONT] [FONT="]http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T3C-3WF7YPF-B&_user=10&_coverDate=04/15/1999&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1574325932&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=5187cdb85cbe922475ced4c14ac47bc0&searchtype=a[/FONT]
[FONT="]Cảm ơn anh chị nhiều![/FONT]
[/FONT]http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CTN-4BT8FD9-7&_user=10&_coverDate=12/31/2003&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1574302749&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=14d25cbd30f3794187ea53e6dc148d3f&searchtype=a
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[/FONT] [FONT="]http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T3C-3WF7YPF-B&_user=10&_coverDate=04/15/1999&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1574325932&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=5187cdb85cbe922475ced4c14ac47bc0&searchtype=a[/FONT]
[FONT="]Cảm ơn anh chị nhiều![/FONT]